U.S. patent application number 12/224804 was filed with the patent office on 2009-07-23 for oled and fabricating method of the same.
Invention is credited to Min-Soo Kang, Jung-Hyoung Lee, Jeoung-Kwen Noh.
Application Number | 20090184628 12/224804 |
Document ID | / |
Family ID | 38475099 |
Filed Date | 2009-07-23 |
United States Patent
Application |
20090184628 |
Kind Code |
A1 |
Kang; Min-Soo ; et
al. |
July 23, 2009 |
Oled and Fabricating Method of the Same
Abstract
The present invention provides an organic light emitting device
comprising: a substrate; a first conductive layer and a second
conductive layer, which are sequentially positioned on the
substrate; and at least one organic material layer, including a
light emitting layer, which is interposed between the first
conductive layer and the second conductive layer; wherein the
organic light emitting device comprises a pattern layer formed
corresponding to the light emitting region between at least one
organic material layer and at least one conductive layer of the
first conductive layer and the second conductive layer; charges are
injected or transported between the conductive layer and the
organic material layer through the pattern layer; and charges are
not directly injected or transported in the region in which two
layers each in contact with the upper surface and the lower surface
of the pattern layer are directly in contact, and a method for
preparation thereof.
Inventors: |
Kang; Min-Soo; (Daejeon
Metropolitan City, KR) ; Noh; Jeoung-Kwen; (Daejeon
Metropolitan City, KR) ; Lee; Jung-Hyoung; (Daejeon
Metropolitan City, KR) |
Correspondence
Address: |
MCKENNA LONG & ALDRIDGE LLP
1900 K STREET, NW
WASHINGTON
DC
20006
US
|
Family ID: |
38475099 |
Appl. No.: |
12/224804 |
Filed: |
March 7, 2007 |
PCT Filed: |
March 7, 2007 |
PCT NO: |
PCT/KR2007/001127 |
371 Date: |
September 5, 2008 |
Current U.S.
Class: |
313/504 ;
427/66 |
Current CPC
Class: |
H01L 51/5092 20130101;
H01L 51/5056 20130101; H01L 51/5088 20130101; H05B 33/10 20130101;
H01L 51/504 20130101; H01L 27/3239 20130101; H01L 27/3209 20130101;
H01L 51/5004 20130101 |
Class at
Publication: |
313/504 ;
427/66 |
International
Class: |
H01J 1/63 20060101
H01J001/63; B05D 5/12 20060101 B05D005/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 7, 2006 |
KR |
10-2006-0021365 |
Claims
1. An organic light emitting device comprising: a substrate; a
first conductive layer and a second conductive layer, which are
sequentially positioned on the substrate; and at least one organic
material layer, including a light emitting layer, which is
interposed between the first conductive layer and the second
conductive layer; wherein the organic light emitting device
comprises a pattern layer formed cor-responding to the light
emitting region between at least one organic material layer and at
least one conductive layer of the first conductive layer and the
second conductive layer; charges are injected or transported
between the conductive layer and the organic material layer through
the pattern layer; and charges are not directly injected or
transported in the region in which two layers each in contact with
the upper surface and the lower surface of the pattern layer are
directly in contact.
2. The organic light emitting device according to claim 1, wherein
the pattern layer is formed of organic materials, inorganic
materials, or a mixture thereof.
3. The organic light emitting device according to claim 1, wherein
the first conductive layer is a cathode electrode, and the second
conductive layer is an anode electrode.
4. The organic light emitting device according to claim 1, wherein
the first conductive layer is an anode electrode, and the second
conductive layer is a cathode electrode.
5. The organic light emitting device according to claim 4, wherein
the pattern layer between the anode electrode and the organic
material layer is a hole injecting layer or a hole transporting
layer.
6. The organic light emitting device according to claim 4, wherein
the pattern layer between the cathode electrode and the organic
material layer is a hole blocking layer, an electron transporting
layer, or an electron injecting layer.
7. The organic light emitting device according to claim 1, wherein
the organic material layer further comprises at least one selected
from the group consisting of a hole injecting layer (HIL), a hole
transporting layer (HTL), a hole blocking layer (HBL), an electron
transporting layer (ETL), and an electron injecting layer
(EIL).
8. The organic light emitting device according to claim 1, wherein
the light generated from the organic material layer is emitted in
the direction to the substrate (bottom emission), in the opposite
direction to the substrate (top emission), or the both.
9. The organic light emitting device according to claim 1, wherein
the pattern layer is an n-type organic material layer in contact
with at least one conductive layer of the first conductive layer
and the second conductive layer, and the organic material layer in
contact with the pattern layer is a p-type organic material layer,
which will form an NP junction with the pattern layer.
10. The organic light emitting device according to claim 9, wherein
Fermi level of the conductive layer, the LUMO energy level of the
pattern layer, and the HOMO energy level of the organic material
layer in contact with the pattern layer satisfy the following
equations (1) and (2): 0eV<E.sub.nL-E.sub.F1.ltoreq.4eV (1)
E.sub.pH-E.sub.nL.ltoreq.1eV (2) wherein in the equations (1) and
(2), E is the Fermi energy level of the conductive layer, E is the
LUMO energy level of the pattern layer, and E is L pH the HOMO
energy level of the organic material layer which would form an NP
junction with the pattern layer.
11. The organic light emitting device according to claim 9, wherein
the n-type organic material layer has a LUMO energy level of 4 to 7
eV, and an electron mobility of 10.sup.-8 cm.sup.2/Ns to 1
cm.sup.2/Ns.
12. The organic light emitting device according to claim 9, wherein
the n-type organic material layer comprises a compound of the
following formula 1: ##STR00004## wherein in the formula 1, R.sup.1
to R.sup.6 are each selected from the group consisting of hydrogen,
a halogen atom, nitrile (--CN), nitro (--NO.sub.2), sulfonyl
(--SO.sub.2R), sulfoxide (--SOR), sulfonamide (--SO.sub.2NR),
sulfonate (--SO.sub.3R), trifluoromethyl (--CF.sub.3), ester
(--COOR), amide (--CONHR or --CONRR'), substituted or
un-substituted linear or branched C.sub.1-C.sub.12 alkoxy,
substituted or unsubstituted linear or branched C.sub.1-C.sub.12
alkyl, substituted or unsubstituted aromatic or non-aromatic
heterocycle, substituted or unsubstituted aryl, substituted or
unsubstituted mono-arylamine or di-arylamine, and substituted or
unsubstituted aralkylamine, and R and R' are each selected from the
group consisting of substituted or unsubstituted C.sub.1-C.sub.60
alkyl, substituted or unsubstituted aryl, and substituted or
unsubstituted 5- to 7-membered heterocycle.
13. The organic light emitting device according to claim 12,
wherein the compound of the formula 1 is selected from the
compounds represented by the following formulae 1-1 to 1-6:
##STR00005## ##STR00006##
14. The organic light emitting device according to claim 1, wherein
the pattern layer is in contact with at least one conductive layer
of the first conductive layer and the second conductive layer, and
the pattern layer is formed of materials selected from the group
consisting of LiF, NaF, CsF, Ca, Mg, CaO, and MgO.
15. A stacked organic light emitting device comprising: a first
conductive layer; at least one intermediate conductive layer; a
second conductive layer; and at least one organic material layer,
including a light emitting layer, which is each disposed between
the conductive layers; wherein the stacked organic light emitting
device comprises a pattern layer formed corresponding to the light
emitting region between at least one of the conductive layers and
at least one organic material layer; charges are injected or
transported between the conductive layer and the organic material
layer through the pattern layer; and charges are not directly
injected or transported in the region in which two layers each in
contact with the upper surface and the lower surface of the pattern
layer are directly in contact.
16. The stacked organic light emitting device according to claim
15, wherein a pattern layer is provided between each conductive
layer and the organic material layer disposed on the conductive
layer.
17. The stacked organic light emitting device according to claim
15, which comprises two or more pattern layers, these pattern
layers having the same or different patterns.
18. The stacked organic light emitting device according to claim
15, wherein comprises a third conductive layer disposed between the
first conductive layer and the second conductive layer; comprises
at least one organic material layer, including a light emitting
layer, on and below the third conductive layer; and comprises a
pattern layer formed corresponding to the light emitting region
between at least one organic material layer and at least one
conductive layer of the first conductive layer, the second
conductive layer and the third conductive layer.
19. A display device comprising the organic light emitting device
according to claim 1.
20. A method of preparing an organic light emitting device
comprising: the steps of sequentially stacking a first conductive
layer, at least one organic material layer including a light
emitting layer, and a second conductive layer on a substrate;
wherein the method comprises a step of forming a pattern layer
corresponding to the light emitting region between at least one
organic material layer and at least one conductive layer of the
first conductive layer and the second conductive layer using
materials which allow charges to be injected or transported between
the conductive layer and the organic material layer through the
pattern layer; a step of forming two layers each in contact with
the upper surface and the lower surface of the pattern layer using
materials which allow charges not to be directly injected or
transported in the region in which two layers are directly in
contact.
Description
TECHNICAL FIELD
[0001] The present invention relates to an organic light emitting
device, and to a method for preparation thereof. More specifically,
the present invention relates to an organic light emitting device
comprising a pattern layer which is capable of lowering the energy
barrier from an electrode for charge injection or charge extraction
to an organic material layer, and to a method for preparation
thereof.
[0002] This application claims priority benefits from Korean Patent
Application No. 10-2006-0021365, filed on Mar. 7, 2006, the entire
contents of which are fully incorporated herein by reference.
BACKGROUND ART
[0003] An organic light emitting device typically includes two
electrodes, and an organic material layer interposed between the
anode and the cathode, in which electric current is converted into
visible light by injecting electrons and holes to the organic
material layer, thereby emitting light.
[0004] FIG. 1 is a schematic diagram which illustrates a
cross-sectional diagram of a general organic light emitting device
as one of the conventional organic light emitting devices.
[0005] With reference to FIG. 1, the organic light emitting device
comprises a light emitting layer (50) interposed between two
electrodes, for example, an anode electrode (20), and a cathode
electrode (70). Any one of the two electrodes, for example, the
anode electrode (20) is disposed on a transparent substrate (10),
and transmits light emitted from the light emitting layer (50). The
organic light emitting device can further comprise at least one
layer selected from the group consisting of an electron injecting
layer (65), an electron transporting layer (60), a hole
transporting layer (45), and a hole injecting layer (40) in order
to improve the performance. Further, the organic light emitting
device can comprise an insulating layer (30) on the electrode of
the transparent substrate (10) in order to distinguish the light
emitting region (A) from the non-light emitting region (B).
[0006] The two electrodes (20, 70) can be formed of a metal, a
metal oxide or a conductive polymer. The materials for forming the
electrodes can have unstable characteristics on the interface with
the organic material layer. Further, heat applied from the outside,
internal heat which can be generated upon driving the organic light
emitting device, and the electrical field applied to the organic
light emitting device can give an adverse effect on the performance
of the device. The drive voltage can be increased for the device
operation due to the difference in the conductive energy level
between the electron/hole injecting layer (65/40) or the
electron/hole transporting layer (60/45), and the organic material
layer.
[0007] Accordingly, it is important to minimize the energy barrier
to electron/hole injection/extraction from or to the electrode, and
it is also important to stabilize the interface between the
electron/hole injecting layer or electron/hole transporting layer,
and the organic material layer, and thus a technique for improving
this can be developed.
[0008] For this, for the anode electrode of the organic light
emitting device, a material having HOMO (highest occupied molecular
orbital) energy level such that the anode electrode is modulated to
have a Fermi energy level similar to the HOMO energy level of the
hole injecting layer, or having a HOMO energy level similar to the
Fermi energy level of the anode electrode is selected as a hole
injecting layer.
[0009] Since the hole injecting layer should be selected, taking
into consideration not only the Fermi energy level of the anode
electrode, but also the HOMO energy level of the hole transporting
layer or the light emitting layer, there is some limitation on
selection of the materials for the hole injecting layer.
Accordingly, a method for modulating the Fermi energy of the anode
electrode is generally employed for the preparation of the organic
light emitting device.
DISCLOSURE OF INVENTION
Technical Problem
[0010] It is an object of the present invention to provide an
organic light emitting device which allows light emission
corresponding to the shapes of the pattern layer by forming the
pattern layer which is capable of lowering the energy barrier to
hole or electron-injecting or transporting between the electrode
and the organic material layer, and a method for preparation
thereof.
[0011] It is another object of the present invention to provide an
organic light emitting device comprising an electrode formed of a
wider range of materials by forming the pattern layer which is
capable of lowering the energy barrier to hole or
electron-injecting or transporting between the electrode and the
organic material layer, and a method for preparation thereof.
Technical Solution
[0012] In order to solve the above-described objects, the present
invention provides an organic light emitting device comprising: a
substrate; a first conductive layer and a second conductive layer,
which are sequentially positioned on the substrate; and at least
one organic material layer, including a light emitting layer, which
is interposed between the first conductive layer and the second
conductive layer; wherein the organic light emitting device
comprises a pattern layer formed corresponding to the light
emitting region between at least one organic material layer and at
least one conductive layer of the first conductive layer and the
second conductive layer; charges are injected or transported
between the conductive layer and the organic material layer through
the pattern layer; and charges are not directly injected or
transported in the region in which two layers each in contact with
the upper surface and the lower surface of the pattern layer are
directly in contact.
[0013] The present invention provides a stacked organic light
emitting device comprising: a first conductive layer; at least one
intermediate conductive layer; a second conductive layer; and at
least one organic material layer, including a light emitting layer,
which is each disposed between the conductive layers; wherein the
stacked organic light emitting device comprises a pattern layer
formed corresponding to the light emitting region between at least
one of the conductive layers and at least one organic material
layer; charges are injected or transported between the conductive
layer and the organic material layer through the pattern layer; and
charges are not directly injected or transported in the region in
which two layers each in contact with the upper surface and the
lower surface of the pattern layer are directly in contact.
[0014] Further, the present invention provides a method of
preparing an organic light emitting device comprising: the steps of
sequentially stacking a first conductive layer, at least one
organic material layer including a light emitting layer, and a
second conductive layer on a substrate; wherein the method
comprises a step of forming a pattern layer corresponding to the
light emitting region between at least one organic material layer
and at least one conductive layer of the first conductive layer and
the second conductive layer using materials which allow charges to
be injected or transported between the conductive layer and the
organic material layer through the pattern layer; a step of forming
two layers each in contact with the upper surface and the lower
surface of the pattern layer using materials which allow charges
not to be directly injected or transported in the region in which
two layers are directly in contact.
ADVANTAGEOUS EFFECTS
[0015] The organic light emitting device according to the present
invention has an effect of lowering the electrical barrier to hole
or electron injection in the interface between the conductive layer
and the organic material layer, by incorporating a pattern layer
between the conductive layer and the organic material layer. Thus,
the present invention has an advantage of improving the light
emitting mechanism by improving the charge injecting ability.
Further, electrodes formed of a wider range of materials can be
provided by forming a pattern layer which is capable of lowering
the electrical barrier to charge injection in the interface between
the electrode and the organic material layer. Further, the stacked
structure has an advantage that a plurality of pattern layers can
be formed in different forms, thereby realizing various light
emitting forms.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates a cross-sectional diagram of the
conventional organic light emitting device,
[0017] FIG. 2 illustrates a cross-sectional diagram of the organic
light emitting device according to a first embodiment of the
present invention,
[0018] FIG. 3 illustrates a cross-sectional diagram of the organic
light emitting device according to a second embodiment of the
present invention,
[0019] FIG. 4 illustrates a cross-sectional diagram of the organic
light emitting device according to a third embodiment of the
present invention.
NUMERAL REFERENCE
[0020] 10, 100, 200, 300; Substrate [0021] 50, 140, 240; Light
emitting layer [0022] 80, 180, 280, 380a, 380b; Organic material
layer [0023] 20, 70; Electrode [0024] 30; Insulating layer [0025]
110, 210, 310; First conductive layer [0026] 170, 270, 370; Second
conductive layer [0027] 358; Third conductive layer [0028] 120,
260, 320, 360; Pattern layer
MODE FOR THE INVENTION
[0029] Here in below, the present invention will be described in
detail. The organic light emitting device according to the present
invention is an organic light emitting device comprising: a
substrate; a first conductive layer and a second conductive layer,
which are sequentially positioned on the substrate; and at least
one organic material layer, including a light emitting layer, which
is interposed between the first conductive layer and the second
conductive layer; wherein the organic light emitting device
comprises a pattern layer formed corresponding to the light
emitting region between at least one organic material layer and at
least one conductive layer of the first conductive layer and the
second conductive layer; charges are injected or transported
between the conductive layer and the organic material layer through
the pattern layer; and charges are not directly injected or
transported in the region in which two layers each in contact with
the upper surface and the lower surface of the pattern layer are
directly in contact. Specifically, the present invention can
provide an organic light emitting device having a light emission
region corresponding to the shapes of the pattern layer by using
the pattern layer which is capable of lowering the electrical
barrier for hole or electron-injection or transport between the
electrode and the organic material layer.
[0030] According to the present invention, the light generated from
the organic material layer can be emitted in the direction to the
substrate (bottom emission), in the opposite direction to the
substrate (top emission), or the both.
[0031] According to the present invention, the pattern layer is
formed of organic materials, inorganic materials, or a mixture
thereof, and the materials are not particularly limited as long as
they have energy levels which allow charges to be injected or
transported between the conductive layer and the organic material
layer through the pattern layer. The pattern layer can serve as at
least one of the organic material layers constituting the
conventional organic light emitting devices, such as a hole
injecting layer, a hole transporting layer, a hole blocking layer,
an electron transporting layer, or an electron injecting layer. In
addition, it may not serve as an additional other layer, as long as
it does not give any adverse effect on the charge transfer of the
device. For example, if the conductive layer in contact with the
pattern layer is an anode, the pattern layer can be composed of
materials for a hole injecting layer, or a hole transporting layer.
Further, if the conductive layer in contact with the pattern layer
is a cathode, the pattern layer can be composed of materials for a
hole blocking layer, an electron transporting layer, or an electron
injecting layer.
[0032] In the present invention, the materials for two layers each
in contact with the upper surface and the lower surface of the
pattern layer are not particularly limited, as long as each layer
has a suitable energy level such that charges are not directly
injected or transported in the region between two layers, and does
not give any adverse effect on the driving the entire device.
[0033] In the present invention, the first conductive layer, and
the second conductive layer may be an anode electrode and a cathode
electrode, respectively, or a cathode electrode, and an anode
electrode, respectively.
[0034] According to one embodiment of the present invention, the
pattern layer is an n-type organic material layer in contact with
at least one conductive layer of the first conductive layer and the
second conductive layer, and the organic material layer in contact
with the pattern layer, being a p-type organic material layer,
which will form an NP junction with the pattern layer. The Fermi
level of the conductive layer, the LUMO energy level of the pattern
layer, and the HOMO energy level of the organic material layer in
contact with the pattern layer can satisfy the following equations
(1) and (2):
0eV <E.sub.nL-E.sub.F1.ltoreq.4eV (1)
E.sub.pH-E.sub.nL.ltoreq.1eV (2)
[0035] In the above equations (1) and (2), E.sub.F1 is the Fermi
energy level of the conductive layer, E.sub.nL is the LUMO energy
level of the pattern layer, and E.sub.pH is the HOMO energy level
of the organic material layer, which would form an NP junction with
the pattern layer. Further, the n-type organic material layer can
have a LUMO energy level of 4 to 7 eV, and an electron mobility of
10.sup.-8 cm.sup.2/Vs to 1 cm.sup.2/Vs.
[0036] In the above embodiment, the conductive layer in contact
with the pattern layer may be a first conductive layer, or a second
conductive layer. If the conductive layer in contact with the
pattern layer is the first conductive layer, the second conductive
layer may be formed of Aluminum (Al), silver (Ag), or materials for
a transparent electrode, such as ITO. The organic material layer
can further comprise at least one layer selected from the group
consisting of a hole injecting layer (HIL), a hole transporting
layer (HTL), an electron transporting layer (ETL), and an electron
injecting layer (EIL). In the above embodiment, a pattern layer can
be further incorporated between the second conductive layer and the
organic material layer, and in this case, the additional pattern
layer can be composed of at least one selected from the group
consisting of LiF, NaF, CsF, Ca, Mg, and MgO.
[0037] The present invention further provides a stacked organic
light emitting device comprising: a first conductive layer; at
least one intermediate conductive layer; a second conductive layer;
and at least one organic material layer, including a light emitting
layer, which is each disposed between the conductive layers;
wherein the stacked organic light emitting device comprises a
pattern layer formed corresponding to the light emitting region
between at least one of the conductive layers and at least one
organic material layer; charges are injected or transported between
the conductive layer and the organic material layer through the
pattern layer; and charges are not directly injected or transported
in the region in which two layers each in contact with the upper
surface and the lower surface of the pattern layer are directly in
contact.
[0038] The stacked organic light emitting device according to the
present invention preferably comprises both of the pattern layer
between each conductive layer and the organic material layer
disposed thereon. If the device comprises two or more pattern
layers, these pattern layers may have the same or different
patterns. By forming various forms of the pattern layers comprising
multiple layers, various light emitting forms can be
accomplished.
[0039] According to one embodiment of the present invention, the
device comprises a third conductive layer disposed between the
first conductive layer and the second conductive layer; comprises
at least organic material layer including a light emitting layer on
and below the third conductive layer; and comprises a pattern layer
formed corresponding to the light emitting region between at least
one organic material layer of the first conductive layer, the
second conductive layer, and the third conductive layer. In this
case, the first conductive layer, the second conductive layer, and
the third conductive layer are each electrically connected with
each other at a ground potential, and an alternating current
voltage can be applied to the third conductive layer, but not
limited thereto.
[0040] The organic light emitting device can be used for display
devices, which can be in turn used for an audio display, an
advertising display, a logo display, a domestic display appliance,
or the like.
[0041] Further, the present invention provides a method of
preparing an organic light emitting device comprising: the steps of
sequentially stacking a first conductive layer, at least one
organic material layer including a light emitting layer, and a
second conductive layer on a substrate; wherein the method
comprises a step of forming a pattern layer corresponding to the
light emitting region between at least one organic material layer
and at least one conductive layer of the first conductive layer and
the second conductive layer using materials which allow charges to
be injected or transported between the conductive layer and the
organic material layer through the pattern layer; a step of forming
two layers each in contact with the upper surface and the lower
surface of the pattern layer using materials which allow charges
not to be directly injected or transported in the region in which
two layers are directly in contact.
[0042] According to one embodiment of the present invention, there
is provided a method of preparing the organic light emitting
device, comprising a step of forming a fust conductive layer on a
substrate; a step of forming a pattern layer corresponding to the
light emitting region on the first conductive layer; a step of
forming at least organic material layer, including a light emitting
layer, on the exposed portion of the first conductive layer and the
pattern layer; and a step of forming a second conductive layer on
the organic material layer, wherein the pattern layer is formed of
materials which allow charges to be injected or transported between
the first conductive layer and the organic material layer through
the pattern layer; and the organic material layer in contact with
the pattern layer is formed of materials which does not allows
direct charge injection or transport from the first conductive
layer in the region in contact with the first conductive layer. The
first conductive layer can be formed of an anode electrode, and the
second conductive layer can be formed of a cathode electrode. The
pattern layer of the anode electrode can be formed of a hole
injecting layer, or a hole transporting layer. Moreover, the
pattern layer can be formed of an n-type organic material, and the
organic material layer in contact with the pattern layer can be
formed of a p-type organic material.
[0043] According to another embodiment of the present invention,
there is provided a method of preparing the organic light emitting
device, comprising a step of forming a first conductive layer on a
substrate; a step of forming at least organic material layer,
including a light emitting layer, on the first conductive layer; a
step of forming a pattern layer corresponding to the light emitting
region on the organic material layer; and a step of forming a
second conductive layer on the exposed portion of the organic
material layer and the pattern layer, wherein the pattern layer is
formed of materials which allow charges to be injected or
transported between the second conductive layer and the organic
material layer through the pattern layer; and the organic material
layer in contact with the pattern layer is formed of materials
which does not allows direct charge injection or transport from the
second conductive layer in the region in contact with the second
conductive layer. The first conductive layer can be formed of an
anode electrode, and the second conductive layer can be formed of a
cathode electrode. The pattern layer formed in the lower surface of
the cathode electrode can be formed of a hole blocking layer, an
electron transporting layer, or an electron injecting layer.
[0044] According to another embodiment of the present invention,
there is provided a method of preparing the organic light emitting
device, comprising a step of forming a first conductive layer on a
substrate; a step of forming a first pattern layer cor-responding
to the light emitting region on the first conductive layer; a step
of forming at least organic material layer, including a light
emitting layer, on the exposed portion of the first conductive
layer and the first pattern layer; a step of forming a second
pattern layer corresponding to the light emitting region on the
organic material layer; and a step of forming a second conductive
layer on the exposed portion of the organic material layer and the
second pattern layer, wherein the first pattern layer is formed of
materials which allow charges to be injected or transported between
the first conductive layer and the organic material layer through
the first pattern layer; the organic material layer in contact with
the first pattern layer is formed of materials which does not
allows direct charge injection or transport from the first
conductive layer in the region in contact with the first conductive
layer; the second pattern layer is formed of materials which allow
charges to be injected or transported between the second conductive
layer and the organic material layer through the second pattern
layer; the organic material layer in contact with the second
pattern layer is formed of materials which does not allows direct
charge injection or transport from the second conductive layer in
the region in contact with the second conductive layer.
[0045] According to another embodiment of the present invention,
there is provided a method of preparing the organic light emitting
device, comprising a step of forming a first conductive layer on a
substrate; a step of forming a first pattern layer cor-responding
to the light emitting region on the first conductive layer; a step
of forming at least first organic material layer, including a light
emitting layer, on the exposed portion of the first conductive
layer and the first pattern layer; a step of forming a third
conductive layer on the first organic material layer; a step of
forming a second pattern layer corresponding to the light emitting
region on the third conductive layer; a step of forming at least
second organic material layer, including a light emitting layer, on
the exposed portion of the third conductive layer and the second
pattern layer; and a step of forming a second conductive layer on
the second organic material layer, wherein the first pattern layer
is formed of materials which allow charges to be injected or
transported between the first conductive layer and the organic
material layer through the first pattern layer; the organic
material layer in contact with the first pattern layer is formed of
materials which does not allows direct charge injection or
transport from the first conductive layer in the region in contact
with the first conductive layer; the second pattern layer is formed
of materials which allow charges to be injected or transported
between the third conductive layer and the second organic material
layer through the second pattern layer; the organic material layer
in contact with the second pattern layer is formed of materials
which does not allows direct charge injection or transport from the
third conductive layer in the region in contact with the third
conductive layer.
[0046] Here in below, preferable embodiments of the present
invention will be described in detail with reference to the
figures. However, the below-described embodiments will be provided
by way of examples for the purpose of clearly explaining the spirit
if the present invention to a skilled person in the art. Thus, the
present invention is not limited to the below-described
embodiments, and certain modifications of the following preferable
embodiments will be made. In these specification, the same
reference numerals are used to indicate like components.
[0047] FIG. 2 is a cross-sectional diagram of the organic light
emitting device according to a first embodiment.
[0048] With reference to FIG. 2, the first conductive layer (110),
and the second conductive layer (170) are sequentially disposed on
the substrate (100). The first conductive layer (110) can be an
anode electrode, and the second conductive layer (170) can be a
cathode electrode.
[0049] The pattern layer (120) is provided between the first
conductive layer (110) and the second conductive layer (170), that
is, in contact with the first conductive layer (110). Here, the
region corresponding to the pattern layer (120) will be a light
emitting region (A), and the remaining region will be a non-light
emitting region (B). The organic material layers (180) are disposed
on the exposed portions of the first conductive layer (110) and the
pattern layer (120). The organic material layers (180) include the
light emitting layer (140), and can further include at least one
selected from the group consisting of a hole injecting layer (130),
a hole transporting layer (135), an electron transporting layer
(150), and an electron injecting layer (155).
[0050] If the first conductive layer (110) is an anode electrode,
the hole injecting layer (130) and the first conductive layer (110)
have energy levels such that holes are not injected from the first
conductive layer (110) to the hole injecting layer (130) in the
region where they are in contact with each other. Further, the
pattern layer (120), the first conductive layer (110) in contact
with the pattern layer (120), and the hole injecting layer (130) in
contact with the pattern layer (120) have energy levels such that
holes can be injected from the first conductive layer (110) to the
hole injecting layer (130) through the pattern layer (120). By
this, charges are injected and transported only in the region
corresponding to the light emitting region (A), that is, the region
of the pattern layer (120), thereby emitting light.
[0051] The pattern layer (120) can be formed of organic materials.
Preferably, the pattern layer (120) can be an n-type organic
material layer, and the hole injecting layer (130) in contact with
the pattern layer (120) can be a p-type organic material layer. In
this case, the pattern layer (120) and the hole injecting layer
(130) will form an NP junction. Here, the Fermi level of the fust
conductive layer, that is, the anode electrode (110), the LUMO
energy level of the pattern layer (120), and the HOMO energy level
of the hole transporting layer (130) preferably satisfy the
following equations (1) and (2):
0eV <E.sub.nL-E.sub.F1.ltoreq.4eV (1)
E.sub.pH-E.sub.nL.ltoreq.1eV (2)
[0052] In the above equations (1) and (2), E.sub.F1 is the Fermi
energy level of the first conductive layer, E.sub.nL is the LUMO
energy level of the pattern layer, and E.sub.pH is the HOMO energy
level of the organic material layer, which would form an NP
junction with the pattern layer.
[0053] Therefore, by incorporating the pattern layer (120) between
the first conductive layer (110) of the organic light emitting
device, that is, the anode electrode, and the hole injecting layer
(130), the electrical barrier to the charge injection can be
lowered at the interface between the first conductive layer and the
organic material layer. As a result, the charge injecting ability
can be improved, and thus electrodes formed of a wider range of
materials can be provided.
[0054] The n-type organic material layer can comprise a compound of
the following formula 1:
##STR00001##
[0055] wherein in the formula 1, R.sup.1 to R.sup.6 are each
selected from the group consisting of hydrogen, a halogen atom,
nitrile (--CN), nitro (--NO.sub.2), sulfonyl (--SO.sub.2R),
sulfoxide (--SOR), sulfonamide (--SO.sub.2NR), sulfonate
(--SO.sub.3R), trifluoromethyl (--CF.sub.3), ester (--COOR), amide
(--CONHR or --CONRR'), substituted or unsubstituted linear or
branched C.sub.1-C.sub.12, alkoxy, substituted or unsubstituted
linear or branched C.sub.1-C.sub.12 alkyl, substituted or
unsubstituted aromatic or non-aromatic heterocycle, substituted or
un-substituted aryl, substituted or unsubstituted mono-arylamine or
di-arylamine, and substituted or unsubstituted aralkylamine. In
addition, R and R' are each selected from the group consisting of
substituted or unsubstituted C.sub.1-C.sub.60 alkyl, substituted or
un-substituted aryl, and substituted or unsubstituted 5- to
7-membered heterocycle.
[0056] Specific examples of the compound of the formula 1 include
the compounds represented by the following formulae 1-1 to 1-6:
##STR00002## ##STR00003##
[0057] The light generated from the organic material layer (180)
can be emitted in the direction to the substrate (100) (bottom
emission), in the opposite direction to the substrate (100) (top
emission), or the both.
[0058] FIG. 3 illustrates a cross-sectional diagram of the organic
light emitting device according to a second embodiment of the
present invention.
[0059] With reference to FIG. 3, unlike the first embodiment, in
the second embodiment, the pattern layer (260) is disposed to be in
contact with the second conductive layer (270). Specifically, the
pattern layer (260) corresponding to the light emitting region (A),
which is in contact with the second conductive layer (270), among
the second conductive layer (270) and the first conductive layer
(210) disposed on the substrate (200) is provided. The first
conductive layer (210) can be an anode electrode, and the second
conductive layer (270) can be a cathode electrode. The organic
material layer (280) is interposed between the pattern layer (260),
and the exposed portion of the second conductive layer (270) and
the first conductive layer (210). The organic material layer (280)
comprises the light emitting layer (240), and can further comprise
at least one selected from the group consisting of the hole
injecting layer (230), the hole transporting layer (235), the
electron transporting layer (250), and the electron injecting layer
(255).
[0060] The electron injecting layer (255) in contact with the
pattern layer (260), and the second conductive layer (270) have
energy levels such that electrons are not injected from the second
conductive layer (270) to the electron injecting layer (255) in the
region where they are in contact with each other. Further, the
pattern layer (260), the second conductive layer (270) in contact
with the pattern layer (260), and the electron injecting layer
(255) in contact with the pattern layer (260) have energy levels
such that electrons can be injected from the second conductive
layer to the electron injecting layer (255) through the pattern
layer (260). By this, charges are injected and transported only in
the region corresponding to the light emitting region (A), that is,
the region of the pattern layer (260), thereby emitting light.
[0061] Specifically, in the first embodiment, a pattern layer in
contact with the anode electrode is provided in the region
corresponding to the light emitting region to minimize the energy
barrier between the anode electrode and the organic material layer,
and thus to improve the hole injecting ability. On the other hand,
in the second embodiment, a pattern layer in contact with the
cathode electrode is provided in the region corresponding to the
light emitting region to minimize the energy barrier between the
cathode electrode and the organic material layer. As a result, in
the second embodiment, the electron injecting ability is improved,
thereby accomplishing a patterned light emitting device.
[0062] The pattern layer (260) can be formed of inorganic
materials. Preferably, it can be formed of any one selected from
the group consisting of LiF, NaF, CsF, Ca, Mg, and MgO. Further, it
can be formed of materials for a hole blocking layer, an electron
transporting layer, or an electron injecting layer. Here, the
second conductive layer (270), that is, the cathode electrode can
be formed of aluminum (Al), silver (Ag), or a transparent electrode
(ITO).
[0063] The organic light emitting device having such structure can
also be a bottom emission device, a top emission device, or a
top-and-bottom emission device.
[0064] FIG. 4 illustrates a cross-sectional diagram of the organic
light emitting device according to a third embodiment of the
present invention.
[0065] With reference to FIG. 4, in the third embodiment, there is
suggested a stacked structure, comprising at least two organic
material layers (380a, 380b). Specifically, a third conductive
layer (358) is disposed between the first conductive layer (310)
and the second conductive layer (370), and the first organic
material layer (380a) and the second organic material layer (380b)
are disposed on and below the third conductive layer (358),
respectively.
[0066] Further, the pattern layers (320, 360) can be disposed on
the first conductive layer (310) and/or the third conductive layer
(358), and alternatively or additionally, on the lower surface of
the first conductive layer (310) and/or the second conductive layer
(370). Here, the first conductive layer (310) and the second
conductive layer (370), and the third conductive layer (358) are
electrically connected with each other at a ground potential, and
an alternating current voltage can be applied to the third
conductive layer (358) to apply a drive voltage required for the
organic light emitting device.
[0067] The third embodiment also has an advantage that a pattern
layer can be formed in the region corresponding to the light
emitting region (A) to minimize the energy barrier between the
conductive layer and the organic material layer, to enhance the
charge mobility, and thus to control the light emitting mechanism.
Further, by incorporating several forms of the pattern layers on
each conductive layer, various light emitting forms, such as top
emission device, bottom emission, and top-and-bottom emission, can
be accomplished.
[0068] In the first through third embodiments, the organic light
emitting device can be used for display devices, which can be in
turn used for one selected from the group consisting of an audio
display, an advertising display, a logo display, and a domestic
display appliance.
[0069] With reference to FIGS. 2 to 4, the preparation method
according to the present invention will be described as
follows.
[0070] With reference to FIG. 2, as for the method of preparing the
organic light emitting device according to a first embodiment of
the present invention, first, a first conductive layer (110) is
formed on a substrate (100). The substrate (100) can be formed of
glass or plastic materials, and in the case of forming a bottom
emission type of an organic light emitting device, it is preferable
to form a transparent substrate. Further, the first conductive
layer (110) can be preferably formed of a metal, a metal oxide or a
conductive polymer.
[0071] The pattern layer (120) is formed on the first conductive
layer (110). Using the processes such as dry or wet etching,
deposition using a fine metal mask, and printing, the pattern layer
(120) can be formed. The region corresponding to the pattern layer
(120) will be a light emitting region (A), and the remaining region
will be a non-light emitting region (B).
[0072] The organic material layer (180) is formed on the first
conductive layer (110) exposed through the pattern layer (120), and
the pattern layer (120). The organic material layer (180) is formed
by stacking at least one selected from the hole injecting layer
(130), the hole transporting layer (135), the light emitting layer
(140), the electron transporting layer (150), and the electron
injecting layer (155).
[0073] The hole injecting layer (130) in contact with the pattern
layer (120) among the organic material layers, have energy levels
such that holes are not directly injected from the first conductive
layer (110) in the region where it is in contact with the first
conductive layer (110). Further, the first conductive layer (110),
the pattern layer (120), and the hole injecting layer (130) each
have energy levels such that holes can be injected and transported
from the first conductive layer (110) to the hole injecting layer
(130) through the pattern layer (120).
[0074] The second conductive layer (170) is formed on the organic
material layer (180) formed as above using a conductive material.
The second conductive layer (170) can be formed of aluminum (Al),
silver (Ag), or a transparent electrode (ITO). The first conductive
layer (110) can be formed of the anode electrode, and the second
conductive layer (170) can be formed of the cathode electrode.
Moreover, the pattern layer (120) on the anode electrode (110) can
be formed of the hole injecting layer, or the hole transporting
layer.
[0075] Further, the pattern layer (120) is formed of an n-type
organic material, and the hole injecting layer (130) can be formed
of a p-type organic material. Here, the Fermi level of the first
conductive layer (110), the HOMO energy level of the hole injecting
layer (130), and the LUMO energy level of the pattern layer (120)
preferably satisfy the above-described equations (1) and (2).
[0076] With reference to FIG. 3, a method for preparing the organic
light emitting device according to a second embodiment of the
present invention is described as follows.
[0077] First, the first conductive layer (210) is formed on the
substrate (200). The substrate (200) can be a transparent substrate
as in the first embodiment, and the first conductive layer (210)
can be formed of a conductive material film. The organic material
layer (280) is formed on the first conductive layer (210). The
organic material layer (280) is formed, which comprises the light
emitting layer (240), and can further comprise at least one
selected from the group consisting of the hole injecting layer
(230), the hole transporting layer (235), the electron transporting
layer (250), and the electron injecting layer (255). The organic
material layer (280) is formed to be in contact with the pattern
layer (260).
[0078] The region corresponding to the region where the pattern
layer (260) is formed will be a light emitting region (A), and the
remaining region will be a non-light emitting region (B). The
pattern layer (260) can be formed, using the processes such as
etching, deposition using a fine metal mask, and printing, as
described above. Further, the pattern layer (260) can be formed of
at least one selected from the group consisting of LiF, NaF, CsF,
Ca, Mg, MgO, and CaO.
[0079] The second conductive layer (270) is formed on the electron
injecting layer (255) exposed through the pattern layer (260), and
the pattern layer (260). Here, the electron injecting layer (255),
and the second conductive layer (270) have energy levels such that
electrons are not directly injected from the second conductive
layer (270) to the electron injecting layer (255) in the region
where they are in contact with each other. Further, the second
conductive layer (270), the pattern layer (270), and the electron
injecting layer (255) each have energy levels such that electrons
can be injected from the second conductive layer (270) to the
electron injecting layer (255) through the pattern layer (270). The
second conductive layer (270) can be formed of aluminum (Al),
silver (Ag), or a transparent electrode (ITO).
[0080] Further, the first conductive layer (210) can be formed of
the anode electrode, and the second conductive layer (270) can be
formed of the cathode electrode. Here, the pattern layer (280)
formed below the cathode electrode can be formed of the hole
blocking layer, the electron transporting layer, or the electron
injecting layer.
[0081] With reference to FIG. 4, a method for preparing the organic
light emitting device according to a third embodiment of the
present invention is described as follows. In the present
embodiment, an organic light emitting device in which at least two
organic material layer units are stacked is formed. That is, as in
the first embodiment, the first conductive layer (310) is formed on
the substrate (300), the first pattern layer (320) is formed
corresponding to the light emitting region (A) on the first
conductive layer (310), and then the first organic material layer
(380a) is formed on the first pattern layer (320), and the first
conductive layer (310) exposed through the first pattern layer
(320). However, unlike the first embodiment where the second
conductive layer is formed on the first organic material layer
(380a), the third conductive layer (358) is formed on the first
organic material layer (380a) prior to forming the second
conductive layer (370).
[0082] Then, the second pattern layer (360) is formed on the third
conductive layer (358). The second pattern layer can be formed,
which corresponds to another light emitting region (C). The second
organic material layer (380b) is formed on the second pattern layer
(360), and the third conductive layer (358) exposed through the
second pattern layer (360), and the second conductive layer (370)
is formed on the second organic material layer (380b).
[0083] Another third pattern layer can be formed between the first
organic material layer (380a) and the third conductive layer (358),
and/or between the second organic material layer (380b) and the
second conductive layer (370). If the third pattern layer is
formed, the third pattern layer can be formed of the hole blocking
layer, the electron transporting layer, or the electron injecting
layer.
[0084] The pattern layer, the conductive layer in contact with the
pattern layer, and the organic material layer in contact with the
pattern layer allow charges to be injected or transported through
the pattern layer, respectively, and they have energy levels such
that charges are not injected or transported from the conductive
layer to the organic material layer in the region where the
conductive layer is in contact with the organic material layer.
[0085] The first pattern layer (320), or the second pattern layer
(360) can be formed of the hole injecting layer, or the hole
transporting layer. Further, the first pattern layer (320), or the
second pattern layer (360) can be an n-type organic material layer,
and the first organic material layer (380a), or the second organic
material layer (380b) can be a p-type organic material layer. The
characteristics of the n-type organic material layer and the p-type
organic material layer are the same as for the organic materials in
the first embodiment.
[0086] In the third embodiment, the pattern layers having the
above-described charac-teristics can be formed to lower the
electrical barrier to the charge mobility in the light emitting
region, and thus to improve the charge injecting ability. Further,
various forms of pattern layers having multiple layers can be
formed to accomplish various light emitting forms.
[0087] While the present invention is described with reference to
preferable embodiments, those skilled in the art will appreciate
that a variety of changes and modifications can be made without
departing from the spirit and the scope of the present invention,
as described in the following claims.
* * * * *